1. Field of the Invention
This invention relates to kerfed gypsum wallboard panels.
2. Description of the Prior Art
Kerfed gypsum wallboard panels are not new to the construction industry. In such panels, the kerfing comprises a slot running the length of the edges, usually the longer edges of the gypsum wallboard panels, and for attachment some type of clip or runner device is inserted into the kerfing with the runner device or clip being attached to some type of support structure, such as a slotted stud. Generally, gypsum wallboard panels having kerfed edges also have some type of hardening or strengthing in the kerfed outer edge portion. Such hardening or strengthening is well known in the gypsum wallboard panel industry and can be accomplished by numerous methods, such as addition or sugar solutions or other hardening materials to the outer edge portions during formation. In previous designs for kerfed gypsum wallboard panels, however, the kerfing has run the entire length of the edge portions, into and including the corner portions thereof, thereby causing a weakening of the corner portions. This weakening of the corner portions, caused by the kerfing, creates breakage at the corner portions thereby creating an undesirable feature in the panels.
Kerfing the center portion of the edge of construction materials is not new. U.S. Pat. No. 3,437,360, shows a siding material which is provided with a kerf which terminates short of the corner of the bottom of the siding, but the kerf of the siding panel extends all the way to and through the top corner thereof. While the top corner of the siding may well be covered so that breakage is not a key feature of the design, breakage nevertheless occurs, and if applied to gypsum wallboard panels where the corners thereof are exposed to view, the gypsum wallboard panels would be undesirable with that design. In U.S. Pat. No. 1,659,326, a frangible facing is attached by a back portion comprising metal sheathed lumber with the metal sheathed lumber being kerfed to accept an attachment device and with the kerfing terminating from the ends thereof. This patent, however, shows the attachment of panel systems without kerfing of the panel system and requires the expensive backup feature to make attachment through a kerfing feature. In German Pat. No. 636,334, a paving system is described using tongue and groove-like formation but having kerfing intermediate to the corners of hard tile and having a piece of wood inserted into the kerfing. In this case, however, a back portion of the edge is removed so that in addition to the kerfing, a laminate material can be placed in the back portion of the edge to absorb movement of the paving system to keep the facing portion thereof from breaking. This feature would be highly undesirable when applied to gypsum wallboard panels since it would create movement or separation of the seam when stress was applied to the panel, and the separation at the seam would make the wall created thereby have an unacceptable appearance.
The new and novel kerfed wallboard panels of this invention have kerfing at opposing edges thereof with the kerfing extending substantially the length of the edges, but terminating prior to the corners of the panel a distance sufficient to prevent weakening of the corners of the panels. The result of such a design is a gypsum wallboard panel having sufficient strength at the corners to prevent breakage under normal handling, but still having all of the advantages of a kerfed installation.